Southern and Northern Nigeria united in 1914 and declared independence from the United Kingdom in 1960.
Barroso expressed remorse over Tuesday's attack in Yobe state in northeastern Nigeria. In a briefing on the meeting, the commission said Barroso "announced a program of $20.5 million aimed at reinforcing the security capabilities of the Nigerian police forces."
Vanguard, a Nigerian newspaper, put the death toll at 43 and attributed the attack on a school in the northeastern state to Islamic militant group Boko Haram.
A Wednesday statement from U.N. Secretary-General Ban Ki-moon described the attacks as "brutal" and without justification.
The Nigerian government in January said Boko Haram attacks in northern Nigerian states that left at least 150 people dead.
Jonathan declared states of emergency for northern states in response to heightened Boko Haram activity last year.